A track circuit apparatus for a train, the track circuit apparatus includes: a ground-based transmitter that is installed corresponding to each of a plurality of block sections divided from a track circuit formed by rails, digitally modulates transmission data by a carrier frequency predetermined and common for each of the block sections, assigns different pseudo random noise (PN) codes to adjacent block sections, and modulates and transmits the data; and a ground-based receiver or an on-train receiver that demodulates received data corresponding to a block section based on the carrier frequency of one of reception signals received from the block section and the PN code assigned to the block section.